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Henning Heuer - One of the best experts on this subject based on the ideXlab platform.

  • automated detection of yarn orientation in 3d draped carbon fiber fabrics and preforms from Eddy Current data
    Composites Part B-engineering, 2016
    Co-Authors: Georg Bardl, Henning Heuer, Martin Schulze, Andreas Nocke, Chokri Cherif, Matthias Pooch, Marko Schiller, Richard Kupke, Marcus Klein
    Abstract:

    Abstract Ensuring the correct fiber orientation in draped textiles and 3D preforms is one of the Current challenges in the production of carbon-fiber reinforced plastics (CFRP), especially in resin transfer molding (RTM). Small deviations in fiber angle during preforming have a considerable effect on the mechanical properties of the final composite. Therefore, this paper presents an automated method for determining local yarn orientation in three-dimensionally draped, multi-layered fabrics. The draped fabric is scanned with a robot-guided High-Frequency Eddy Current sensor to obtain an image of the sample's local conductivity and permittivity. From this image, the fiber orientation not only of the upper, but also of the lower, optically non-visible layers can be analyzed. A 2D Fast Fourier Transform is applied to local segments of the Eddy Current image to determine the local yarn orientation. Guidelines for processing the Eddy Current data, including phase rotation, filtering and evaluation segment size, are derived. For an intuitive visualization and analysis of the determined yarn orientation, reference yarn paths are reconstructed from the determined yarn angles. The developed process can be applied to quality inspection, process development and the validation of forming simulation results.

  • non destructive evaluation nde of composites Eddy Current techniques
    Non-Destructive Evaluation (NDE) of Polymer Matrix Composites, 2013
    Co-Authors: Henning Heuer, Martin Schulze, Norbert Meyendorf
    Abstract:

    Abstract: Industrial mass-producing carbon fiber reinforced polymer (CFRP) processes (e.g. resin transfer molding) require non-destructive testing (NDT) methods that can be applied to dry textile multilayer materials and to final components as well. Questions to be solved are fiber orientations, gaps, local defects, etc. By analyzing the electrical properties of carbon fiber materials – the fiber distribution and the dielectric properties can be inspected non-destructively. Based on High-Frequency Eddy Current techniques, structural and hidden defects such as missing carbon fiber bundles, lanes, fringes and angle deviations for hidden layers can also be detected. Carbon fiber based materials show a low electrical conductivity, which is sufficient to measure deviations in the material by using Eddy Current techniques. Eddy Current methods show a high potential for inline integration due to the absence of couplings, e.g., compared to ultrasonic.

  • textural analyses of carbon fiber materials by 2d fft of complex images obtained by high frequency Eddy Current imaging hf eci
    Proceedings of SPIE, 2012
    Co-Authors: Martin Schulze, Henning Heuer
    Abstract:

    Carbon fiber based materials are used in many lightweight applications in aeronautical, automotive, machine and civil engineering application. By the increasing automation in the production process of CFRP laminates a manual optical inspection of each resin transfer molding (RTM) layer is not practicable. Due to the limitation to surface inspection, the quality parameters of multilayer 3 dimensional materials cannot be observed by optical systems. The Imaging Eddy- Current (EC) NDT is the only suitable inspection method for non-resin materials in the textile state that allows an inspection of surface and hidden layers in parallel. The HF-ECI method has the capability to measure layer displacements (misaligned angle orientations) and gap sizes in a multilayer carbon fiber structure. EC technique uses the variation of the electrical conductivity of carbon based materials to obtain material properties. Beside the determination of textural parameters like layer orientation and gap sizes between rovings, the detection of foreign polymer particles, fuzzy balls or visualization of undulations can be done by the method. For all of these typical parameters an imaging classification process chain based on a high resolving directional ECimaging device named EddyCus® MPECS and a 2D-FFT with adapted preprocessing algorithms are developed.

  • experimental based discussion for the separation of residual stresses and cold work in shot peened in718 using high frequency Eddy Current spectroscopy
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION VOLUME 29, 2010
    Co-Authors: Susanne Hillmann, Henning Heuer, H U Baron, J Bamberg, A Robbert, Norbert Meyendorf
    Abstract:

    Typical aero engine alloys, such as IN718, can be surface‐treated by shot peening to induce near‐surface compressive strains. To calculate the remaining operation time for those critical aero engine components, a quantitative nondestructive determination of near‐surface strain gradients has to be developed. We have demonstrated in the past, that it is possible to obtain a characteristic depth profile (surface and sub‐surface) of the electrical conductivity of shot peened specimen by using high‐frequency Eddy Current techniques. The measured conductivity profile is resulting from residual stresses, cold work, surface roughness, and the microstructure of the material. The objective is to measure residual stresses (separately from other material properties) in such components after a defined life time. It can be assumed, that surface roughness and microstructure remain unchanged in IN718 materials over their lifetime, but cold work and residual stresses can change independently. Consequently, there is a need...

  • experimental based discussion for the separation of residual stresses and cold work in shot peened in718 using high frequency Eddy Current spectroscopy
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION VOLUME 29, 2010
    Co-Authors: Susanne Hillmann, Henning Heuer, J Bamberg, A Robbert, Hansuwe Baron, Norbert Meyendorf
    Abstract:

    Typical aero engine alloys, such as IN718, can be surface‐treated by shot peening to induce near‐surface compressive strains. To calculate the remaining operation time for those critical aero engine components, a quantitative nondestructive determination of near‐surface strain gradients has to be developed. We have demonstrated in the past, that it is possible to obtain a characteristic depth profile (surface and sub‐surface) of the electrical conductivity of shot peened specimen by using high‐frequency Eddy Current techniques. The measured conductivity profile is resulting from residual stresses, cold work, surface roughness, and the microstructure of the material. The objective is to measure residual stresses (separately from other material properties) in such components after a defined life time. It can be assumed, that surface roughness and microstructure remain unchanged in IN718 materials over their lifetime, but cold work and residual stresses can change independently. Consequently, there is a need to clearly separate the information from both material properties of received Eddy Current conductivity signals in order to obtain specific information related to residual stresses. This paper presents results acquired from different experiments, conducted to separate both effects by using the Eddy Current technique on shot peened IN718 materials. We present different physical approaches and illustrate the experiments to solve them. In addition, we will demonstrate that there is a need to use additional techniques, for example ultrasonic time‐of‐flight measurements, to separate the effects of residual stresses from compound (mixed) signals obtained on cold work samples.

A M Frishman - One of the best experts on this subject based on the ideXlab platform.

  • conductivity profile determination by Eddy Current for shot peened superalloy surfaces toward residual stress assessment
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION, 2007
    Co-Authors: Y Shen, C C H Lo, A M Frishman, N Nakagawa
    Abstract:

    This paper describes an Eddy Current model‐based method for inverting near‐surface conductivity deviation profiles of surface treated materials from swept‐high frequency Eddy Current (SHFEC) data. This work forms part of our Current research directed towards the development of an electromagnetic nondestructive technique for assessing residual stress of shot‐peened superalloy components. The inversion procedure is based on the use of a parameterized function to describe the near‐surface conductivity as a function of depth for a shot‐peened surface, and the laterally uniform multi‐layer theory of Cheng, Dodd and Deeds to calculate the resulting coil impedance deviations. The convergence of the inversion procedure has been tested against synthesized Eddy Current data. As a demonstration, the conductivity deviation profiles of a series of Inconel 718 specimens, shot peened at various Almen intensities, have been obtained by inversion. Several consistency tests were conducted to examine the reliability of the ...

  • conductivity profile determination by Eddy Current for shot peened superalloy surfaces toward residual stress assessment
    Journal of Applied Physics, 2007
    Co-Authors: Y Shen, C C H Lo, N Nakagawa, A M Frishman
    Abstract:

    This paper demonstrates a swept high frequency Eddy Current (SHFEC) methodology that can determine near-surface conductivity deviation profiles of shot-peened superalloy surfaces, from which residual stress state can be assessed nondestructively. Our methodology is built around a laboratory-grade SHFEC hardware and a model-based SHFEC data inversion software, both described in this article. For the demonstration, a series of shot-peened Inconel 718 block specimens is prepared and examined by the proposed SHFEC inversion technique. The conductivity depth profiles of the samples under various shot peening intensities have been obtained by the inversion. Several sensitivity and consistency test results are given to support the reliability of the inverted conductivity profiles. The extreme near-surface regions (10–20μm) of the shot-peened surfaces are also examined by various microstructural characterization methods such as scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffract...

Norbert Meyendorf - One of the best experts on this subject based on the ideXlab platform.

  • non destructive evaluation nde of composites Eddy Current techniques
    Non-Destructive Evaluation (NDE) of Polymer Matrix Composites, 2013
    Co-Authors: Henning Heuer, Martin Schulze, Norbert Meyendorf
    Abstract:

    Abstract: Industrial mass-producing carbon fiber reinforced polymer (CFRP) processes (e.g. resin transfer molding) require non-destructive testing (NDT) methods that can be applied to dry textile multilayer materials and to final components as well. Questions to be solved are fiber orientations, gaps, local defects, etc. By analyzing the electrical properties of carbon fiber materials – the fiber distribution and the dielectric properties can be inspected non-destructively. Based on High-Frequency Eddy Current techniques, structural and hidden defects such as missing carbon fiber bundles, lanes, fringes and angle deviations for hidden layers can also be detected. Carbon fiber based materials show a low electrical conductivity, which is sufficient to measure deviations in the material by using Eddy Current techniques. Eddy Current methods show a high potential for inline integration due to the absence of couplings, e.g., compared to ultrasonic.

  • experimental based discussion for the separation of residual stresses and cold work in shot peened in718 using high frequency Eddy Current spectroscopy
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION VOLUME 29, 2010
    Co-Authors: Susanne Hillmann, Henning Heuer, J Bamberg, A Robbert, Hansuwe Baron, Norbert Meyendorf
    Abstract:

    Typical aero engine alloys, such as IN718, can be surface‐treated by shot peening to induce near‐surface compressive strains. To calculate the remaining operation time for those critical aero engine components, a quantitative nondestructive determination of near‐surface strain gradients has to be developed. We have demonstrated in the past, that it is possible to obtain a characteristic depth profile (surface and sub‐surface) of the electrical conductivity of shot peened specimen by using high‐frequency Eddy Current techniques. The measured conductivity profile is resulting from residual stresses, cold work, surface roughness, and the microstructure of the material. The objective is to measure residual stresses (separately from other material properties) in such components after a defined life time. It can be assumed, that surface roughness and microstructure remain unchanged in IN718 materials over their lifetime, but cold work and residual stresses can change independently. Consequently, there is a need to clearly separate the information from both material properties of received Eddy Current conductivity signals in order to obtain specific information related to residual stresses. This paper presents results acquired from different experiments, conducted to separate both effects by using the Eddy Current technique on shot peened IN718 materials. We present different physical approaches and illustrate the experiments to solve them. In addition, we will demonstrate that there is a need to use additional techniques, for example ultrasonic time‐of‐flight measurements, to separate the effects of residual stresses from compound (mixed) signals obtained on cold work samples.

  • experimental based discussion for the separation of residual stresses and cold work in shot peened in718 using high frequency Eddy Current spectroscopy
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION VOLUME 29, 2010
    Co-Authors: Susanne Hillmann, Henning Heuer, H U Baron, J Bamberg, A Robbert, Norbert Meyendorf
    Abstract:

    Typical aero engine alloys, such as IN718, can be surface‐treated by shot peening to induce near‐surface compressive strains. To calculate the remaining operation time for those critical aero engine components, a quantitative nondestructive determination of near‐surface strain gradients has to be developed. We have demonstrated in the past, that it is possible to obtain a characteristic depth profile (surface and sub‐surface) of the electrical conductivity of shot peened specimen by using high‐frequency Eddy Current techniques. The measured conductivity profile is resulting from residual stresses, cold work, surface roughness, and the microstructure of the material. The objective is to measure residual stresses (separately from other material properties) in such components after a defined life time. It can be assumed, that surface roughness and microstructure remain unchanged in IN718 materials over their lifetime, but cold work and residual stresses can change independently. Consequently, there is a need...

  • near surface residual stress profiling with high frequency Eddy Current conductivity measurement
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Proceedings of the#N#35th Annual Review of Progress in Quantitative Nondestructive Evalu, 2009
    Co-Authors: Susanne Hillmann, Henning Heuer, H U Baron, J Bamberg, A Yashan, Norbert Meyendorf
    Abstract:

    The lifetime of aero engine components can be extended by applying an additional strain to the material. Typical aero engine‐alloys like Nickel‐Base superalloys or Titanium alloys can be surface‐treated by use of shot peening to induce the compressive strain near the surface. However, in order to use the additional life for critical aero engine components, a quantitative determination of strain gradients near the surface has to be carried out periodically. We propose to measure the depth‐profile of residual stresses non‐destructively by use of high frequency Eddy Current techniques. This paper presents results obtained with an experimental set‐up based on a high precision impedance analyzer. Test samples prepared from IN718 by shot peening of different intensities can be easily distinguished. By sweeping the frequency from 100 kHz up to 100 MHz a depth profile for the electrical conductivity from 50 μm to 500 μm can be obtained. The measured conductivity profile is a resultant from residual stresses, cold...

Y Shen - One of the best experts on this subject based on the ideXlab platform.

  • conductivity profile determination by Eddy Current for shot peened superalloy surfaces toward residual stress assessment
    REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION, 2007
    Co-Authors: Y Shen, C C H Lo, A M Frishman, N Nakagawa
    Abstract:

    This paper describes an Eddy Current model‐based method for inverting near‐surface conductivity deviation profiles of surface treated materials from swept‐high frequency Eddy Current (SHFEC) data. This work forms part of our Current research directed towards the development of an electromagnetic nondestructive technique for assessing residual stress of shot‐peened superalloy components. The inversion procedure is based on the use of a parameterized function to describe the near‐surface conductivity as a function of depth for a shot‐peened surface, and the laterally uniform multi‐layer theory of Cheng, Dodd and Deeds to calculate the resulting coil impedance deviations. The convergence of the inversion procedure has been tested against synthesized Eddy Current data. As a demonstration, the conductivity deviation profiles of a series of Inconel 718 specimens, shot peened at various Almen intensities, have been obtained by inversion. Several consistency tests were conducted to examine the reliability of the ...

  • conductivity profile determination by Eddy Current for shot peened superalloy surfaces toward residual stress assessment
    Journal of Applied Physics, 2007
    Co-Authors: Y Shen, C C H Lo, N Nakagawa, A M Frishman
    Abstract:

    This paper demonstrates a swept high frequency Eddy Current (SHFEC) methodology that can determine near-surface conductivity deviation profiles of shot-peened superalloy surfaces, from which residual stress state can be assessed nondestructively. Our methodology is built around a laboratory-grade SHFEC hardware and a model-based SHFEC data inversion software, both described in this article. For the demonstration, a series of shot-peened Inconel 718 block specimens is prepared and examined by the proposed SHFEC inversion technique. The conductivity depth profiles of the samples under various shot peening intensities have been obtained by the inversion. Several sensitivity and consistency test results are given to support the reliability of the inverted conductivity profiles. The extreme near-surface regions (10–20μm) of the shot-peened surfaces are also examined by various microstructural characterization methods such as scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffract...

Peter B Nagy - One of the best experts on this subject based on the ideXlab platform.

  • high frequency Eddy Current conductivity spectroscopy for residual stress profiling in surface treated nickel base superalloys
    Ndt & E International, 2007
    Co-Authors: Bassam A Abunabah, Peter B Nagy
    Abstract:

    Abstract Recent research results indicated that Eddy Current conductivity measurements can be exploited for nondestructive evaluation of subsurface residual stresses in surface-treated nickel-base superalloy components. Most of the previous experimental studies were conducted on highly peened (Almen 10-16A) specimens that exhibited harmful cold work in excess of 30% plastic strain. Such high level of cold work causes thermo-mechanical relaxation at relatively modest operational temperatures; therefore the obtained results were not directly relevant to engine manufacturers and end users. The main reason for choosing peening intensities in excess of recommended normal levels was that in low-conductivity engine alloys the Eddy Current penetration depth could not be forced below 0.2 mm without expanding the measurements above 10 MHz which is beyond the operational range of most commercial Eddy Current instruments. In this paper we report the development of a new High-Frequency Eddy Current conductivity measuring system that offers an extended inspection frequency range up to 50 MHz with a single spiral coil. In addition to its extended frequency range, the new system offers better reproducibility, accuracy, and measurement speed than the previously used conventional system.